Influence of different administration routes of live avian encephalomyelitis vaccine during simultaneous administration of live Fowlpox vaccine.

Vaccination is essential for disease control in laying hens. The avian encephalomyelitis (AE) vaccine is administered with the fowlpox (FP) vaccine by wing-web puncture, but its performance during concurrent FP vaccination remains unclear. This study evaluated AE vaccine responses during concurrent FP vaccination. At 56 days of age, hens received AE and FP vaccines simultaneously. In the wing-web group, vaccines were mixed and administered by wing-web puncture. In the drinking water group, the AE vaccine was given in drinking water during FP vaccination. Fecal and blood samples were collected before vaccination and for 8 weeks thereafter. Fecal AE virus was detected by reverse transcription-quantitative polymerase chain reaction, and serum AE antibodies were measured by enzyme-linked immunosorbent assay. AE virus was detected earlier and at higher levels in the drinking water group. Antibody responses also developed earlier, and all birds in this group were seropositive at 8 weeks (8/8), compared with 50% (3/6) in the wing-web group. Because birds were not randomly allocated and different hen strains were included, administration-route effects could not be distinguished from strain- or housing-related influences. Under field conditions, birds in the drinking water group showed stronger AE vaccine responses than those in the wing-web group.